Over time, a variety of endoscopic biopsy forceps, graspers, and other related apparatuses have been developed to take samples of tissue or grasp and remove material during endoscopic procedures. Normally, the forceps, which are adapted to cut and remove body tissue for examination, are inserted together with an endoscope deep into a body cavity being examined. The forceps conventionally used in such procedures utilize complex arrangements of linkage assemblies or cam type devices for articulating the jaws of the forceps. As such instruments are of small size, such complexity results in complex machining and manufacturing procedures which greatly increase the cost of such instruments. The multiple connections also increase the amount of play, which may increase the distortion of the movement of the jaws of the device. Thus, present biopsy devices are generally very expensive and, the jaw actuating mechanisms are complex and may be inaccurate.
The small size and number of the linkages and hinge pins also decrease the durability of the biopsy forceps and make them vulnerably to breakage. This is an important consideration, especially when working within a patient where retrieval of a dissociated part may be difficult or dangerous to the patient. Large numbers of small linkages and hinges-also increase the cost and difficulty of manufacturing and assembly.
The combination of jaws, linkages, and outer housing results in an instrument jaw/housing assembly having a significant rigid length. This rigidity associated with the instrument increases the difficulty of navigation through the bent channel of the endoscope, as well as increasing the potential for damage of the endoscope instrument channel through which the device is passed to obtain a tissue sample. A single endoscope may be used for many endoscopic procedures, and, in some cases an endoscopic biopsy procedure requires multiple insertions and removals of the device. Each insertion or removal of the biopsy instrument through the narrow channel in the endoscope can cause potential damage to the channel of the endoscope or to the biopsy instrument itself. This is especially problematic in cases where a tortuous passage leads to the cavity from which the sample is obtained.
Further damage to the endoscope instrument channel may be caused by a link or a member of the forceps which protrudes from the perimeter of the rest of the forceps. This problem may arise if the forceps are unable to close completely or if a portion of the mechanism jams, or even if the mechanism merely has excess play. When the forceps are inserted or removed from the endoscope under these conditions, the exposed link or member may scrape, scratch or otherwise damage the channel.
Since many current biopsy devices are intended for multiple use, damage to the endoscope or biopsy device itself is even less desirable. Furthermore, in conventional biopsy forceps, the intended multiple use of the instrument requires extensive cleaning and sterilizing procedures to be performed to comply with medical standards and use of the instruments. When used multiple times, a biopsy instrument must be sterilized between uses by immersing a contaminated instrument in a suitable chemical sterilizing solution, subjecting the apparatus to sterilization in an autoclave, or some other sterilization procedure. The sterilization and cleaning procedures will often decrease the performance or useful life span of the instrument, thereby magnifying the problem created by the complexity of manufacture and many parts which quickly wear. Further, some devices which are intended only for single use still incorporate complex linkage or cam type devices for proper movement of the biopsy jaws. This greatly inhibits their use as the costs associated with such instruments are normally still very high.
Other deficiencies of the prior art endoscopic biopsy forceps are found in activation of the biopsy jaws for opening and closing of the jaws. The complexity and many moving parts of prior art devices cause the jaws to misalign when the jaws are actuated. This is also a problem with devices which utilize a living hinge. A living hinge operates by using the flexibility and deformation of the material of the hinge to allow the jaws to move. However, the same flexibility allows the jaws to twist which means that the cutting edges of the jaws may not meet properly and the sample is not removed cleanly from the rest of the organ. In extreme cases, the forceps may fail entirely and require that a new instrument be used and/or a lost piece of the instrument be retrieved from the patient.
Due to their geometry, many prior art devices provide the greatest amount of force from control wire to the jaws when the jaws are in their fully open position, and the least amount of force when the jaws are in their fully closed position. In use, these characteristics are the opposite of what is most efficient and useful. Greater force is need to complete the cutting of the sample and hold the jaws in place during insertion and removal.